Effect of microbial transglutaminase on the structural and rheological characteristics and in vitro digestion of rice glutelin–casein blends

• Published in: Food research international Vol. 139; p. 109832
• Main Authors: He, Chengxin, Hu, Yu, Woo, Meng Wai, Xiong, Hua, Zhao, Qiang
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.01.2021
• Subjects: Casein; crosslinking; digestibility; digestion; disulfides; Fluorescence; food research; FT-IR; hydrogen; In vitro digestion; loss modulus; microstructure; protein-glutamine gamma-glutamyltransferase; proteinases; Rheological; rheology; rice; Rice glutelin; storage modulus; thermal stability; Transglutaminase; Casein; Rice glutelin; Fluorescence; Rheological; FT-IR; Transglutaminase; In vitro digestion
• ISSN: 0963-9969; 1873-7145; 1873-7145
• DOI: 10.1016/j.foodres.2020.109832

[Display omitted] •MTGase cross-linked glutelin and casein is effective way of modifying their properties.•Viscoelastic descrease of glutelin and casein was promoted by MTGase addition (≤15 U)•The maximum MTGase activity can be achieved for cross-linking at 15 U/g of protein.•The MTGase-catalyzed reaction improved the protease resistance of the blends. The effect of microbial transglutaminase (MTGase) in cross-linking and modifying of rice glutelin–casein blends was investigated in this work. The maximum MTGase activity on rice glutelin–casein blends were found when its addition was 15 U/g of protein. Compared with the blends without MTGase, the appropriate addition of MTGase significantly affected the microstructure of the cross-linked proteins, resulting in the gradual ‘burying’ of Trp residue; while the space for hydrogen bonding was more abundant. Secondary structure changes, denoted by the disappearance of the α-helix and the decrement of the β-sheet structure, was due to the formation of the large loop and random coil structures. The MTGase-catalyzed reaction improves the protease resistance of the blends but not promote the conversion of free sulfhydryl groups (-SH) to disulfide groups (S-S). All the samples evaluated exhibited Bingham flow behavior instead of shear-thinning behavior, and thermally stable fluid properties dominated by elasticity, regardless of MTGase concentration used. Both the storage modulus (G') and loss modulus (G'') gradually decreased with the addition of MTGase. In short, this work demonstrated how the structure, rheology, digestibility of rice glutelin-casein blends are influenced by MTGase concentration.